Updates href uses for 516 (#88699)

## About The Pull Request

Was just scrolling through the Paradise github since they seem to have
more work done for 516 to see if there's anything I can port over, found
this and thought why not.

Ports parts of https://github.com/ParadiseSS13/Paradise/pull/25105
Specifically, updaing all hrefs to use the internal ``byond://``, and
adding it to grep.

## Why It's Good For The Game

More work towards 516.

## Changelog

Nothing player-facing.

code/modules/modular_computers/file_system/programs/messenger/messenger_program.dm

@@ -709,7 +709,7 @@
 			reply = "(<a href='byond://?src=[REF(src)];choice=[reply_href];skiprefresh=1;target=[REF(chat)]'>Reply</a>)"
 
 		if (isAI(messaged_mob))
-			sender_title = "<a href='?src=[REF(messaged_mob)];track=[html_encode(sender_name)]'>[sender_title]</a>"
+			sender_title = "<a href='byond://?src=[REF(messaged_mob)];track=[html_encode(sender_name)]'>[sender_title]</a>"
 
 		var/inbound_message = "[signal.format_message()]"